The present invention relates to a printing apparatus, and specifically relates to a printing apparatus capable of automatically erasing a misprinted character string.
Conventionally, in printing apparatuses such as English character typewriters, a mechanism is provided which automatically erases a misprinted word using a correcting ribbon in the case where a misprint happens due to a wrong spelling. For example, as described in the Japanese Patent Laid-Open No. 210482/1985 (This application is claiming priority based on U.S. Pat. No. 4,561,793.), the conventional automatic word correcting apparatus for printing apparatus moves the correcting ribbon in a swing fashion to the print position when correcting the misprinted word, and erases the word from the last character to the head character in sequence. The purpose of such an erasure in the direction reverse to the printing direction is that a printing head is positioned at the position of the head character of the word when the erasure is completed, and thereby the correct word can be immediately re-printed.
The above-mentioned conventional automatic word correcting mechanism for printing apparatus is suitable for an application to the printing apparatus equipped with single printing type such as the daisy wheel.
By the way, in recent years, the thermal head has been applied widely to printing apparatuses such as the English character typewriters.
The applicant of the present patent has put the printing/correcting ribbon as described later into practical use by improving a physical structure of a thermo-transfer ribbon used for printing by the thermal head printing and erasing using a thermo-transfer ribbon and a thermal head is described in Japanese Patent Application No. 249762/1985 and the Japanese Patent Application No. 249763/1985.
At the thermal head, characters and the like are printed in combination of dot strings while the head is moved in the printing direction, and in this connection, the thermo-transfer ribbon is taken-up on a take-up spool from a feed spool only when the thermal head is moved in the printing direction.
Accordingly, when a misprinted word is erased sequentially from the last character to the head character by applying the conventional automatic word correcting apparatus to the thermal printer, such a control is to be repeated that each character is erased while the thermal head is moved in the printing direction, subsequently the thermal head is moved in the direction reverse to the printing direction to the position of character of higher-order side, and then the thermal head is moved again in the printing direction to erase the character. On the other hand, the ribbon can be fed also while moving the thermal head in the direction reverse to the printing direction, but this is complicated in mechanism.
Accordingly, the conventional automatic word correcting apparatus is difficult to be applied to the thermal printer.